Magnetically operated relay switches



Feb. 24, 1970 L. F. STAUDER 3,497,840

MAGNETICALLY OPERATED RELAY SWITCHES Filed Jan. 9, 1969 jammy/Z292" 3 Lawrence Fiaader United States Patent Int. (:1. H01h 51/28, 1/66 U.S. Cl. 335-453 6 Claims ABSTRACT OF THE DISCLOSURE A mercury wetted contact switch and relay in which the sensitivity of the relay and the operating character istics are improved through use of a piece of low reluc tance material between the pole pieces of the switch and the armature stem.

The present invention is directed to mercury wetted contact switches for use in relays and is particularly con cerned with improvements in the magnetic characteristics of the relays.

Mercury wetted contact relays of this type utilize the magnetic flux of an operating coil to bias a movable armature or switch contact element between the contact faces of a pair of switch poles. The direction of flux produced in the operating coil determines the direction in which the armature is moved and, hence, determines the particular contact made with the armature. Relays of this type are sometimes provided with permanent magnets or some other means which bias the armature toward the contact face of one pole or the other in the absence of magnetic flux supplied by the coil, or the armature may be biased by the permanent magnets to a neutral position. Permanent magnets may also be used to form what are known to the art as single side stable, bistable, or center stable relays. The relays may have specific predetermined operating characteristics.

With the present invention it has been discovered that the number of ampere turns required to operate relays of this class can be drastically reduced. This means that relays of this class can be manufactured with a smaller size of coil than has been thought possible heretofore, the cost of copper used in the coils is reduced, less current may be used for operating the relay, and a smaller size of relay can be used in situations where larger relays are impractical. Also, with the present invention it has been discovered that the sensitivity of these relays can be improved. These advantages are realized in the invention through use of a piece of low reluctance material, preferably sealed into the glass envelope of the switch itself between the upstanding poles thereof, and similar material is magnetically associated therewith and extends around the operating coil of the relay to the armature stem of the switch, thus providing a low reluctance path for the magnetic flux from the coil, as well as the magnetic flux from any permanent magnets associated with the relay, to and through the armature. The material provides what is in effect a closed loop of low reluctance material for the magnetic flux with very minor air gaps existing in the overall flux path. With the flux path to 3,497,840 Patented Feb. 24, 1970 and through the armature thus improved, the armature moves towards one or the other contact pieces with a lesser amount of energy or bias from the operating coil or from the permanent magnets.

Other advantages and purposes of the invention will be more apparent in the course of the ensuing specification and claims, when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a front view of a typical mercury wetted contact relay incorporating the principles of the present invention;

FIGURE 2 is a side view of the relay illustrated in FIGURE 1;

FIGURE 3 is a partial sectional view illustrating certain details of the relay construction of FIGURES 1 and 2 taken on a fore and aft section; and

FIGURE 4 is a partial sectional view of the relay of FIGURES l, 2 and 3 and taken on a section between the sides of the relay.

Like elements are designated by like characters throughout the specification and drawings.

Referring now specifically to the drawings, and in the first instance to FIGURE 1, the invention is shown applied to a mercury wetted contact relay of a nonbridging break-before-make type. The switch is essentially the same as shown in OBrien et al. Patent No. 3,054,873 and reference is made to that patent for details of con struction not specifically referred to herein. As shown, 10 designates the glass envelope of the switch. A movable contact or armature 11 is positioned within the switch and is connected to a metallic stem 12 which extends outwardly from one end of the glass envelope as is known to the art. The other end of the glass envelope has a pair of spaced pole pieces 13 and 14 extending through the end of the envelope and into the interior of the envelope to provide contact faces 15 and 16 on opposite sides of the contact end of the armature 11. The pole pieces 13 and 14 are connected to electrical leads while the stem 12 is also connected to an electrical lead in a manner known to the art. The glass envelope carries a body of mercury and the capillary action of the mercury provides a film on the metal of the contact surfaces of the pole pieces and armature. The portions of the pole pieces carrying the contact faces 15 and 16 as well as the armature 11 are sealed Within the glass envelope 10, and the envelope has a permanent gas fill of a suitable gas, such as hydrogen. As shown, the relay makes use of a pair of permanent bar magnets 17 and 18 which are positioned and secured alongside the upper ends of the pole pieces 13 and 14 and which are separated from one another by insulation 19. The polarity of these bar magnets is as illustrated by the letters N and S, designating north and south poles, respectively. It should be understood that other forms of permanent magnets may be used for influencing the armature in a manner known to the art.

An operating coil 20 surrounds the glass envelope 10 in the manner illustrated. In operation of relays of this type, the permanent magnet structure associated with the pole pieces 13 and 14 provides a definite polarity for each of the pole pieces and the contact faces associated therewith, as is designated by the north and south letters N and S, respectively, in the drawings. Then, when electrical current is supplied to the coil, the direction of flux, which depends upon the direction of current, either aids one of the contact faces or the other to move the armature into contact therewith. The position and magnetic strength of the permanent magnets may be so adjusted that the relay is single side stable, bistable, or center stable.

In accordance with the invention, a piece of low reluctance material, such as in the form of a wire 21, is positioned midway between the pole pieces 13 and 14 and preferably embedded in the end of the glass envelope carrying the pole pieces. This wire 21 extends outside of the glass envelope, as is most clearly seen in FIGURE 3. The wire 21 is spaced midway between the pole pieces and extends perpendicular to a line between the pole pieces. It is positioned relatively close to the operating end of the armature 11. A ceramic element 22 extends between the pole pieces, and between the wire 21 and the contact faces of the pole pieces. This spacing element is at the inner side of the glass envelope and the wire 21 is closely adjacent to this spacing element in its embedded position within the envelope. The wire 21 is formed from a high permeability, low residual magnetic material or low reluctance material such as permalloy, vanadium permendur, soft annealed iron or nickel-iron wire. However, the magnetic material that is used should have a coefficient of expansion which reasonably matches the coefficient of expansion of the material used for the switch envelope. For this reason, it has been found that under ordinary circumstances it is desirable to have the wire element 21 made of the same material as the pole pieces 13 and 14, such as nickel iron alloy having approximately 52% nickel and 48% iron. In lieu of a wire, the element 21 may take the form of a strip of low reluctance material.

Additional pieces of low reluctance material 23 and 24 are connected to the opposite ends of the wire 21 and extend around the operating coil 20 and are connected to the stem 12 as by appropriate bending of the strips 23 and 24. The strips 23 and 24 may be formed as a single strip of generally U-shaped form as may be seen in FIG- URE 2, in which case the bight portion of the strip is connected to the stem as at 25 while the legs 23 and 24 of the strip extend over and around the operating coil 20 and have their ends connected to the wire 21, as illustrated.

The connecting strips 23 and 24 are formed of a low reluctance material such as permalloy, vanadium permendur, soft annealed iron or steel or other nickel-iron alloy of low reluctance material. As formed, the connecting strip and wire 21 provide a substantially closed mag netic path of low reluctance between the pole pieces 13 and 14, around the coil 20, through the stem 12, and armature 11.

Flux paths in the connecting loop defined by strips 23 and 24 as well as the pole pieces and armature are indicated by the arrows in FIGURES 1 and 2 but obviously the direction of the flux will depend upon the direction of the current being sent through the coil 20.

It is preferred that the armature 11 also be formed from a material such as permalloy, or vanadium permendur. This material may be nickel plated to improve its mercury wetting characteristic. Vanadium permendur contains approximately 49% cobalt, 2% vanadium, and 49% iron by weight, and permalloy contains approximately 80% nickel and 20% iron by weight.

In operation, and in the absence of flux energy from coil 20, flux paths from the biasing magnets will cause the armature 11 to assume a definite polarity, as, for example, as shown in the drawings in which case it will be noted that the armature 11 is in contact with the contact face 16 with the flux directions as indicated by the arrows. When the coil 20 is then energized with a polarity such that the coil causes armature 11 to be attracted to contact face 15, which in the drawings is shown as having a south polarity, the flux from the coil may then form what is in effect a closed loop through the armature 11, connecting strips 23 and 24, and element 21 so that the armature 11 moves into contact with the south contact face 15 under the influence of the flux paths from contact face 15 as well as from the flux paths from armature 11. In this regard, when the armature 11 is thus given a definite north polarity at its upper end, it is both attracted by the south contact 15 and repelled by the north contact face 16. When the coil is operated with an opposite polarity so as to aid the north contact face 16 of pole 14, the converse is true, because the direction of the flux path through the armature and through connecting strips 23 and 24 and element 21 is then opposite.

It has been found that a relay made in accordance with this disclosure has greatly improved operating characteristics. For example, in a relay of the general type illustrated and arranged for single side stable operation, 60 ampere turns of current may be required in coil 20 to cause operation without the use of the element 21 and connecting strips 23 and 24, whereas with the use of the connecting loop construction of the present invention, the same relay may operate on as little as 5.5 ampere turns. Similarly, a relay of the type illustrated in the drawings When adjusted for bistable operation may require 28 ampere turns for the operation of the relay without the use of the closed loop of the low reluctance material described herein, whereas by using the closed loop defined by the element 21 and connecting strip material 23 and 24, the relay will operate with as little as 3.45 ampere turns of current from coil 20.

The principles of the invention can be used with various types of relay constructions known to the art in addition to the specific form of relay disclosed in the drawings. The principles can be used with separate and additional biasing coils and without magnets, with various forms and arrangements of biasing magnets, contact elements and armatures.

It should also be understood that the form of the electrical coil of the relays can be widely varied. The coils may be single wound, concentric wound or bifilar in form.

Whereas I have shown and described an operative form of the invention, it should be understood that this showing and description thereof should be taken in an illustra tive or diagrammatic sense only. There are modifications to the invention which will fall within the scope and spirit thereof and which will be apparent to those skilled in the art. The scope of the invention should be measured only by the scope of the hereinafter appended claims.

I claim:

1. An electrical relay of the type wherein a movable armature of a switch has a contact end positioned between a pair of contact elements of pole pieces for selective contact therewith under influence of an electrical coil positioned to produce flux paths causing the armature to move into one contact element or the other, the improvement comprising a piece of low reluctance material positioned between the pole pieces of the switch, and having portions extended around the electrical coil and closely adjacent the end of the armature opposite to the end between said contact elements.

2. The structure of claim 1 wherein the switch is of a mercury wetted contact type wherein the contact elements and armature are positioned within a glass-like envelope and the armature has a stem of magnetic material extending beyond one end of the envelope, said portions being closely associated with said stem.

3. The structure of claim 2 wherein said piece of low reluctance material is defined by a wire-like element embedded within said glass-like envelope at a position adjacent to the operating end of said armature and connecting strips of low reluctance material are connected between said wire and said stem, said element extending perpendicular to a plane which includes the pole pieces of the relay.

4. The structure of claim 1 wherein said relay includes permanent magnets associated with said poles for influencing the magnetic characteristics of said contact elements.

5 6 5. An electrical relay as set forth in claim 1 wherein References Cited a movable armature is positioned between a pair of con- UNITED STATES PATENTS tact elements of pole pieces for selective contact therea with under influence of an electrical coil, the improve- 310481677 8/1962 Henstrom et aL X ment comprising the armature being formed of vanadium permendur materiaL 5 BERNARD A. GILHEANY, Primary Examiner 6. The structure of claim 5 wherein the relay is of a R. N. ENVALL, JR., Assistant Examiner type wherein the contact elements and armature are positioned within a glass-like envelope and the armature has a stem extending beyond one end of the envelope. 10 335 57 

